A typical glycoprotein product differs substantially in terms of complexity from a typical small molecule drug. The sugar structures attached to the amino acid backbone of a glycoprotein can vary structurally in many ways including, sequence, branching, sugar content, and heterogeneity. Thus, glycoprotein products can be complex heterogeneous mixtures of many structurally diverse molecules which themselves have complex glycan structures. Glycosylation adds not only to the molecule's structural complexity but affects or conditions many of a glycoprotein's biological and clinical attributes.